TW202404930A - Abating unwanted emulsion polymerization during extractive distillation of conjugated diene monomers - Google Patents

Abstract

Inhibitor compositions for abating undesirable emulsion polymerization during processing of hydrocarbon stream laden with reactive vinylic monomers are provided. The polymerization inhibitor compositions include at least a first inhibitor compound having a stable nitroxide radical and a second inhibitor including phenylenediamine. Methods of inhibiting the polymerization of monomers using the compositions of the disclosure are also provided. The methods of inhibiting polymerization of monomers include a step of adding a composition of the disclosure to a process stream. The process stream includes an ethylenically unsaturated monomer that is suspended in the bulk-phase and highly polar solvents as distractive distillation solvents.

Description

Reduce undesired emulsion polymerization during extractive distillation of conjugated diene monomers

The present disclosure generally relates to compositions including blends of polymerization inhibitors and methods of using the same. More specifically, the present disclosure relates to a composition including at least one compound with stable nitroxide radical and phenylenediamine, which can be used to inhibit the emulsion polymerization of ethylenically unsaturated monomers.

The manufacture of ethylenically unsaturated monomers generally involves three stages: reaction, crude product recovery, and product purification by fractionation. Distillation operations performed at elevated temperatures often involve recovery and purification stages. Ethylenically unsaturated monomers (such as styrene, butadiene, isoprene, divinylbenzene, cyclopentadiene, dicyclopentadiene, vinyl acetate, acrylate, and methacrylate monomers ) found in crude process streams or in refined products manufactured by various chemical industry processes. However, these monomers are highly reactive, especially at elevated temperatures, in the presence of oxygen, or when in contact with metal oxide surfaces. Therefore, these monomer types are highly susceptible to undesired polymerization via free radical polymerization. This problem is serious, especially at elevated temperatures and in the presence of polymerization initiators such as organic peroxides. The resulting polymer can be problematic and lead to equipment "fouling" and product contamination and consumption. Once the resulting polymer precipitates out of solution and deposits onto equipment surfaces during the processing stages, production efficiency is reduced. Due to contamination of process equipment, operations must be suspended to mechanically clean the equipment and/or remove undesired polymers. The cessation of operations resulted in significant financial losses for the operator. Polymers may also remain in solution as soluble product contaminants. Contamination may require additional processing steps to remove the contaminating polymer from the final product component stream or stored product. All of the issues mentioned above have necessitated the development and use of online chemical cleaning processes to reduce fouling and thereby eliminate financially costly operational downtime.

Premature polymerization of such monomers is usually reduced by administering polymerization inhibitors capable of eliminating or significantly reducing premature polymerization of the monomers. Conventional polymerization inhibitors include stable free radicals that can effectively scavenge carbon-centered radicals.

During the extractive distillation of reactive conjugated diene monomers such as butadiene and isoprene, the low polarity monomer system is suspended in a bulk-phase and a highly polar solvent such as N , N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and acetonitrile. Unless effective inhibitors are used, the dispersed monomers will undergo undesirable free radical polymerization. This leads to contamination, which can cause production losses and unanticipated downtime.

Conventional polymerization inhibitors, such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical (HTEMPO) and 4-side oxy-2,2,6,6-tetramethyl Piperidin-1-oxyl radical (OTEMPO) is substantially dispersed in the overall phase, and a small part is in the non-polar droplets of the reactive monomer, which makes it ineffective in preventing emulsion polymerization. .

A composition for inhibiting monomer polymerization is provided. The composition includes a first inhibitor compound including stable nitroxide radicals, and a second inhibitor compound including phenylenediamine.

In some aspects, the first inhibitor compound has Formula (I): (I) wherein R ₁ is a C ₁ -C ₂₂ alkyl or aryl group, wherein the alkyl and aryl groups are optionally substituted with one or more C ₁ -C ₂₂ alkyl or aryl groups.

In some aspects, the first inhibitor is selected from the group consisting of: 1-oxyl-2,2,6,6-tetramethylpiperine-4-ol; 4-methoxy- 2,2,6,6-tetramethylpiperidin-1-oxy; 4-ethoxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-propoxy- 2,2,6,6-tetramethylpiperidin-1-oxy; 4-butoxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-pentyloxy- 2,2,6,6-tetramethylpiperidin-1-oxy; 4-hexyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-heptyloxy- 2,2,6,6-tetramethylpiperidin-1-oxy; 4-octyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-nonyloxy- 2,2,6,6-tetramethylpiperidin-1-oxy; 4-decyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-undecyloxy Base-2,2,6,6-tetramethylpiperidin-1-oxy; 4-dodecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4- Tridecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-tetradecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy base; 4-pentadecyloxy-2,2,6,6-tetramethylpiperidine-1-oxy; 4-hexadecyloxy-2,2,6,6-tetramethylpiperidine -1-oxy; 4-heptadecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-octadecyloxy-2,2,6,6-tetramethyl Methylpiperidin-1-oxy; 4-nonadecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-decyloxy-2,2,6,6 -Tetramethylpiperidin-1-oxy; 4-eicosyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-eicosyloxy-2, 2,6,6-tetramethylpiperidin-1-oxy; 4-docosyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-(phenoxy base) 2,2,6,6-tetramethylpiperidin-1-oxyl; 4-(benzyloxy)-2,2,6,6-tetramethylpiperidin-1-oxyl; 2, 2,6,6-tetramethyl-4-(naphth-2-yloxy)piperidin-1-oxy; and any combination thereof.

In some aspects, the first inhibitor is a compound of Formula III: (III) wherein R ₃ is –O• or –OH; and R ₄ is C ₁ -C ₂₂ alkyl or aryl, wherein the alkyl and aryl groups are optionally modified by one or more C ₁ -C ₂₂ alkyl substituted by aryl or aryl groups.

In some aspects, the first inhibitor is selected from the group consisting of: 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yl acetate; 1-oxyradical Free radical-2,2,6,6-tetramethylpiperidin-4-yl butyrate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yl butyrate ;1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl valerate;1-oxyl radical-2,2,6,6-tetramethylpiperidin-4- Hepanoate; 1-Oxyl-2,2,6,6-tetramethylpiperidin-4-ylheptanoate; 1-Oxyl-2,2,6,6-tetramethylpiperidin Din-4-yloctanoate; 1-Oxyl-2,2,6,6-tetramethylpiperidin-4-ylnonanoate; 1-Oxyl-2,2,6,6- Tetramethylpiperidin-4-yl decanoate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yl undecanoate; 1-oxyradical-2,2 ,6,6-tetramethylpiperidin-4-yl dodecanoate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl stearate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4- 1-oxyl benzoate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl palmitate; 1-oxyl radical-2,2,6,6-tetramethyl Piperidin-4-yl behenate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yl 4-tertiary butyl benzoate; and any combination thereof .

In some aspects, the second inhibitor compound is a phenylenediamine of formula (IV) or formula (V): , (IV) _{( V )} wherein _{X 1 and} Aryl substitution.

In _{some aspects , X 1 and} replace.

In some aspects, _X1 and _X2 are independently _C1 - _C10 alkyl or phenyl, wherein the alkyl and the phenyl are optionally separated by one or more _C1 - _C22 alkyl or aryl groups. base substitution.

_In some _{aspects , X 1 and} replace.

In some aspects, the second inhibitor is selected from the group consisting of: 1,2-phenylenediamine, 1,4-phenylenediamine, N,N'-di-methyl-p-phenylenediamine , N,N'-di-secondary butyl-1,4-phenylenediamine, N,N'-di-1,4-dimethylpentyl-1,4-phenylenediamine, N,N' -Di-ethyl-1,4-phenylenediamine, N-tertiary butyl-N'-phenyl-1,4-phenylenediamine, N,N'-di-phenyl-1,4- Phenylenediamine, and any combination thereof.

In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 80% by weight.

In some aspects, the second inhibitor compound is present in the composition at a concentration of about 0.01% to about 50% by weight.

In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 100:1 to about 1:100.

In some aspects, the composition further includes an organic solvent.

In some aspects, the composition further includes an ethylenically unsaturated monomer selected from the group consisting of: vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, benzene Ethylene, isoprene, acrylic acid, methacrylic acid, and any combination thereof.

Provide a method to inhibit monomer polymerization. The method includes adding a composition to a process stream in an extractive distillation process. The composition includes: a first inhibitor compound including a stable nitroxide radical; and a second inhibitor compound including phenylenediamine. This process flow contains microcells.

In some aspects, the process flow includes a monomer.

In some aspects, the process stream includes a solvent selected from the group consisting of DMF (N,N-dimethylformamide)/furfural, NMP (N-methylpyrrolidone), acetonitrile, and mixtures thereof. Sometimes, stratification or microcells can occur during the extractive distillation process. Two immiscible layers are formed: a non-polar monomer layer and a polar solvent layer.

In some aspects, the ethylenically unsaturated monomer partitions to a greater extent into one of the at least one non-polar distillation solvent than into the at least one polar extractive distillation solvent.

In some aspects, the inhibitor formulation has the ability to partition from the polar solvent layer into the monomer layer to inhibit premature emulsion polymerization in both layers.

In some aspects, the process stream further includes at least one polar extractive distillation solvent and at least one non-polar extractive distillation solvent, the at least one non-polar extractive distillation solvent comprising at least one ethylenically unsaturated monomer.

In some aspects, the at least one polar extractive distillation solvent and the at least one non-polar extractive distillation solvent are immiscible with each other.

In some aspects, the first inhibitor or the second inhibitor partitions to a greater extent into at least one non-polar extractive distillation solvent than into the at least one polar extractive distillation solvent.

In some aspects, the at least one non-polar extractive distillation solvent is furfural, tetrahydrofuran, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, Tetrakane, benzene, toluene, ethylbenzene, ethyltoluene, methylene chloride, tetrachloromethane, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, thirteen Alkene, tetradecene, cyclopentane, cyclopentene, cyclohexane, cyclohexene, dicyclopentane, cyclopentadiene, dicyclopentadiene, ethyl acetate, ethyl propionate, ethyl butyrate Ester, ethyl valerate, ethyl caproate, ethyl enanthate, ethyl, nonanoate, ethyl caprate, ethyl undecanoate, ethyl dodecanoate, ethyl tridecanoate, tetradecanoate Ethyl ester, ethyl pentadecanoate, ethyl hexadecanoate, ethyl octadecenoate, ethyl behenate, methyl acetate, methyl propionate, methyl butyrate, methyl valerate, caproic acid Methyl ester, methyl enanthate, methyl, nonanoate, methyl caprate, methyl undecanoate, methyl dodecanoate, methyl tridecanoate, methyl myristate, methyl pentadecanoate, Methyl hexadecanoate, methyl octadecenoate, methyl behenate, propyl acetate, propyl propionate, propyl butyrate, propyl valerate, propyl caproate, propyl enanthate, propyl Base, nonanoate, propyl caprate, propyl undecanoate, propyl dodecanoate, propyl tridecanoate, propyl myristate, propyl pentadecanoate, propyl hexadecanoate, octadecene Propyl acid, propyl behenate, butyl acetate, butyl propionate, butyl butyrate, butyl valerate, butyl hexanoate, butyl enanthate, butyl, nonanoate, butyl decanoate Ester, butyl undecanoate, butyl dodecanoate, butyl tridecanoate, butyl myristate, butyl pentadecanoate, butyl hexadecanoate, butyl octadecenoate, butyl behenate Ester, hexyl acetate, hexyl propionate, hexyl butyrate, hexyl valerate, hexyl hexanoate, hexyl enanthate, hexyl, nonanoate, hexyl caprate, hexyl undecanoate, dodecanate Hexyl acid, hexyl tridecanoate, hexyl myristate, hexyl pentadecanoate, hexyl hexadecanoate, hexyl octadecenoate, hexyl behenate, octyl acetate, octyl propionate, Octyl butyrate, octyl valerate, octyl caproate, octyl enanthate, octyl, nonanoate, octyl caprate, octyl undecanoate, octyl dodecanoate, octyl tridecanoate, octyl myristate, pentadecanoate Octyl acid, octyl hexadecanoate, octyl octadecenoate, octyl behenate, and any combination thereof.

In some aspects, the at least one non-polar extractive distillation solvent is an alkane, an alkene, a cycloalkane, a cycloalkene, an aryl, an alkylaryl, an arylalkyl, an organic ester, an ether, a cyclic ether, and/or Other non-polar solvents known in the art.

In some aspects, the at least one non-polar extractive distillation solvent is selected from the group consisting of: vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, styrene, Isoprene, cyclopentadiene, dicyclopentadiene, acrylic acid, methacrylic acid, and any combination thereof.

In some aspects, the at least one polar extractive distillation solvent is selected from the group consisting of N,N-dimethylformamide, furfural, N-methylpyrrolidone, acetonitrile, water, and combinations thereof.

In some aspects, the monomer is an ethylenically unsaturated monomer.

In some aspects, the composition is added to the process stream such that the concentration of the first inhibitor compound is from about 0.1 ppm to about 10,000 ppm.

In some aspects, the composition is added to the process stream such that the concentration of the second inhibitor compound is from about 0.1 ppm to about 10,000 ppm.

In some aspects, the monosystem is selected from the group consisting of: vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, styrene, divinylbenzene, iso Pentadiene, cyclopentadiene, dicyclopentadiene, acrylic acid, methacrylic acid, and any combination thereof.

The foregoing has given a rather broad overview of the features and technical advantages of the present invention in order to better understand the following embodiments. Additional features and advantages of the invention will be described hereinafter which form the subject of the patent claims of the present application. It should be understood by those of ordinary skill in the art that the conception and specific aspects disclosed may be readily utilized as a basis for modifying or designing other aspects for carrying out the same purposes of the present disclosure. Those of ordinary skill in the art should also realize that such equivalents do not depart from the spirit and scope of the present disclosure as set forth in the accompanying patent claims.

Various aspects of this disclosure are described below. The relationships and functions of various components of the aspect can be more fully understood with reference to the following embodiments. However, aspects are not limited to those expressly described herein, and it is understood that in some cases, details unnecessary to understanding the aspects disclosed herein may be omitted, such as, for example, conventional synthesis and/or formulation. .

During the extractive distillation of reactive conjugated diene monomers, emulsion polymerization can occur, resulting in undesirable fouling. There is a need for polymerization inhibitors that can effectively prevent emulsion polymerization. The compositions and methods disclosed herein prevent or reduce emulsion polymerization.

Provide a method to inhibit monomer polymerization. The method includes adding a composition to a process stream in an extractive distillation process. The composition includes a first inhibitor compound including stable nitroxide radicals, and a second inhibitor compound including phenylenediamine. This process flow contains microcells.

As used herein, "micelles" refer to aggregates of amphiphilic molecules. Microcells are formed when two immiscible liquids in different amounts are stirred, causing the smaller liquid system to disperse into the overall liquid to form droplets. The dispersed droplets constitute microcells, and the bulk liquid system is a continuous phase.

The present disclosure relates to compositions including blends of polymerization inhibitors and methods of using the same to inhibit the polymerization of ethylenically unsaturated monomers. The polymerization inhibitor composition of the present disclosure includes at least one compound with thermally and chemically stable nitroxide radicals and phenylenediamine. The polymerization inhibitor composition can be a blend of multiple components, including the aforementioned compounds with stable nitroxide radicals and components other than phenylenediamine.

In the presence of polymerizable monomers, a "polymerization inhibitor" inhibits the polymerization of these monomers during the induction time under shutdown conditions. After the induction time has elapsed after the polymerization inhibitor has been completely consumed, polymer formation occurs at the same rate as in the complete absence of the polymerization inhibitor.

Polymerization inhibitors and polymerization retarders can generally be considered "antipolymerants", which are compounds that inhibit or reduce the formation of polymers from one or more radically polymerizable compounds.

The term "fouling" means the formation of polymers, prepolymers, oligomers, and/or other substances that, under the conditions under which the equipment is operated, will become insoluble in the stream and/or precipitate out of the stream and deposited on equipment. In turn, the inhibitor composition of the present disclosure may be referred to as "antifouling" because it inhibits or reduces the formation of fouling polymers. Composition of the present disclosure

The present disclosure relates to a composition for inhibiting monomer polymerization, wherein the composition includes a first inhibitor compound having stable nitroxide radicals and a second inhibitor compound phenylenediamine. In some aspects, the compositions used herein are particularly useful in the high-severity conditions found in distillation columns. In some aspects, the composition is used to inhibit polymerization of a monomer, wherein the monomer is an ethylenically unsaturated monomer. For example, the composition of the present disclosure can be used to inhibit the polymerization of ethylenically unsaturated monomers, including but not limited to vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, styrene , isoprene, acrylic acid, (meth)acrylic acid, and combinations thereof.

In some aspects, the compositions of the present disclosure can be used to inhibit the polymerization of ethylenically unsaturated monomers under highly severe operating conditions.

In some aspects, the first inhibitor compound having a stable nitroxide radical is a compound of formula (I): (I) wherein R ₁ is H, C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, C ₁ -C ₂₂ cycloalkyl, aryl, –C ₁ -C ₂₂ Alkylene, -C(O)(C ₁ -C ₂₂ alkyl), -C(O)(C ₁ -C ₂₂ alkenyl), -C(O)(C ₁ -C ₂₂ alkynyl), –C(O)(C ₁ -C ₂₂ cycloalkyl), –C(O)(aryl), or –C(O)(C ₁ -C ₂₂ alkylene aryl), wherein the alkyl, Cycloalkyl, and aryl groups are optionally substituted with one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl groups.

The term "aryl" refers to monocyclic, bicyclic (fused), and tricyclic (fused or spiro) hydrocarbon ring systems having a total of five to fourteen ring carbon atoms, in which at least one of the The ring system is aromatic, and each ring in the system contains 3 to 7 ring carbon atoms. The term "aryl" is used interchangeably with the term "aryl ring".

In some aspects, R ₁ is –C(O)(C ₁ -C ₂₂ alkyl), –C(O)(C ₁ -C ₂₂ alkenyl), –C(O)(C ₁ -C ₂₂ alkynyl), –C(O)(C ₁ -C ₂₂ cycloalkyl), –C(O)(aryl), or –C(O)(C ₁ -C ₂₂ alkylene aryl), wherein the alkyl, cycloalkyl, and aryl groups are optionally substituted with one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, and aryl groups.

In some aspects, R1 is C ₁ -C ₂₂ alkyl or aryl, wherein the alkyl and aryl groups are optionally substituted with one or more C ₁ -C ₂₂ alkyl or aryl groups.

In some aspects, _R1 is H. In some aspects, R ₁ is C ₁ -C ₂₂ alkyl. In some aspects, R ₁ is C ₁ -C ₂₂ alkenyl. In some aspects, R ₁ is C ₁ -C ₂₂ alkynyl. In some aspects, R ₁ is C ₁ -C ₂₂ cycloalkyl, wherein the cycloalkyl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ - C ₂₂ alkynyl or aryl substitution. In some aspects, R ₁ is aryl, wherein the aryl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl base substitution. In some aspects, R ₁ is -C ₁ -C ₂₂ alkylene aryl, wherein the aryl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl or aryl substitution. In some aspects, R ₁ is -C(O)(C ₁ -C ₂₂ alkyl). In some aspects, R ₁ is -C(O)(C ₁ -C ₁₂ alkyl). In some aspects, R ₁ is –C(O)(C ₁ -C ₆ alkyl). In some aspects, R ₁ is –C(O)(methyl). In some aspects, R ₁ is –C(O)(ethyl). In some aspects, R ₁ is –C(O)(propyl). In some aspects, R ₁ is –C(O)(butyl). In some aspects, R ₁ is -C(O)(C ₁ -C ₂₂ alkenyl). In some aspects, R ₁ is –C(O)(C ₁ -C ₂₂ alkynyl). In some aspects, R ₁ is -C(O)(C ₁ -C ₂₂ cycloalkyl), wherein the cycloalkyl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl substitution. In some aspects, R ₁ is -C(O)(aryl), wherein the aryl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl or aryl substitution. In some aspects, R ₁ is -C(O)(C ₁ -C ₂₂ alkylene aryl), wherein the aryl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ - C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl substitution.

Examples of compounds of formula (I) include, but are not limited to, 1-oxyl-2,2,6,6-tetramethylpiperine-4-ol; 4-methoxy-2,2,6,6- Tetramethylpiperidine-1-oxy; 4-ethoxy-2,2,6,6-tetramethylpiperidine-1-oxy; 4-propoxy-2,2,6,6- Tetramethylpiperidin-1-oxy; 4-butoxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-pentyloxy-2,2,6,6- Tetramethylpiperidin-1-oxy; 4-hexyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-heptyloxy-2,2,6,6- Tetramethylpiperidin-1-oxy; 4-octyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-nonyloxy-2,2,6,6- Tetramethylpiperidin-1-oxy; 4-decyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-undecyloxy-2,2,6, 6-tetramethylpiperidin-1-oxy; 4-dodecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-tridecyloxy-2, 2,6,6-tetramethylpiperidin-1-oxy; 4-tetradecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-pentadecyloxy Base-2,2,6,6-tetramethylpiperidin-1-oxy; 4-hexadecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4- Heptadecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-octadecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy base; 4-nonadecyloxy-2,2,6,6-tetramethylpiperidine-1-oxy; 4-decyloxy-2,2,6,6-tetramethylpiperidine-1 -oxy; 4-eicosyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-eicosyloxy-2,2,6,6-tetramethyl piperidin-1-oxy; 4-docosyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-(phenoxy)2,2,6, 6-tetramethylpiperidin-1-oxy; 4-(benzyloxy)-2,2,6,6-tetramethylpiperidin-1-oxy; or 2,2,6,6-tetramethyl Methyl-4-(naphth-2-yloxy)piperidin-1-oxy.

In other aspects, the first inhibitor compound has formula (II): , (II) wherein R ₂ is selected from H, C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, C ₁ -C ₂₂ cycloalkyl, aryl, –C ₁ -C ₂₂ alkylene, –C(O)(C ₁ -C ₂₂ alkyl), –C(O)(C ₁ -C ₂₂ alkenyl), –C(O)(C ₁ -C ₂₂ alkyne base), –C(O)(C ₁ -C ₂₂ cycloalkyl), –C(O)(aryl), and –C(O)(C ₁ -C ₂₂ alkylene), wherein the alkyl , alkylene, cycloalkyl, and aryl groups are optionally substituted with one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl groups.

In some aspects, R ₂ is –C(O)(C ₁ -C ₂₂ alkyl), –C(O)(C ₁ -C ₂₂ alkenyl), –C(O)(C ₁ -C ₂₂ alkynyl), –C(O)(C ₁ -C ₂₂ cycloalkyl), –C(O)(aryl), and –C(O)(C ₁ -C ₂₂ alkylene), where the Alkyl, alkylene, cycloalkyl, and aryl groups are optionally substituted with one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl groups .

In some aspects, _R2 is H. In some aspects, R ₂ is C ₁ -C ₂₂ alkyl. In some aspects, R ₂ is C ₁ -C ₂₂ alkenyl. In some aspects, R ₂ is C ₁ -C ₂₂ alkynyl. In some aspects, R ₂ is C ₁ -C ₂₂ cycloalkyl, wherein the cycloalkyl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ - C ₂₂ alkynyl or aryl substitution. In some aspects, R ₂ is aryl, wherein the aryl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl base substitution. In some aspects, R ₂ is -C ₁ -C ₂₂ alkylene, wherein the alkylene is optionally substituted with aryl, the aryl is optionally substituted with one or more C ₁ -C ₂₂ alkyl , C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl substitution. In some aspects, R ₂ is –C(O)(C ₁ -C ₂₂ alkyl). In some aspects, R ₂ is –C(O)(C ₁ -C ₁₂ alkyl). In some aspects, R ₂ is –C(O)(C ₁ -C ₆ alkyl). In some aspects, R ₂ is –C(O)(methyl). In some aspects, R ₂ is –C(O)(ethyl). In some aspects, R ₂ is –C(O)(propyl). In some aspects, R ₂ is –C(O)(butyl). In some aspects, R ₂ is –C(O)(C ₁ -C ₂₂ alkenyl). In some aspects, R ₂ is –C(O)(C ₁ -C ₂₂ alkynyl). In some aspects, R ₂ is -C(O)(C ₁ -C ₂₂ cycloalkyl), wherein the cycloalkyl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl substitution. In some aspects, R ₂ is -C(O)(aryl), wherein the aryl is optionally modified by one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ - C ₂₂ alkynyl or aryl substitution. In some aspects, R ₂ is -C(O)(C ₁ -C ₂₂ alkylene), wherein the alkylene is optionally substituted with an aryl, the aryl is optionally substituted with one or more C ₁ -C ₂₂ alkyl, C ₁ -C ₂₂ alkenyl, C ₁ -C ₂₂ alkynyl, or aryl substitution.

In some aspects, the compound of formula (II) is 2,2,6,6-tetramethylpiperine-1,4-diol; 4-methoxy-2,2,6,6-tetramethyl piperidin-1-ol; 4-ethoxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-propoxy-2,2,6,6-tetramethylpiperidin-1-ol Din-1-ol; 4-butoxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-pentoxy-2,2,6,6-tetramethylpiperidin- 1-alcohol; 4-hexyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-heptyloxy-2,2,6,6-tetramethylpiperidin-1- Alcohol; 4-octyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-nonyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-Decanoxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-Undecyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-Dodecyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-Tridecyloxy-2,2,6,6-tetramethylpiperidin-1- Alcohol; 4-tetradecyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-pentadecyloxy-2,2,6,6-tetramethylpiperidin- 1-alcohol; 4-hexadecyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-heptadecyloxy-2,2,6,6-tetramethylpiperidin-1-ol 4-octadecyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-nonadecyloxy-2,2,6,6-tetramethyl piperidin-1-ol; 4-decyloxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-eicosyloxy-2,2,6,6-tetramethyl piperidin-1-ol; 4-docosanoxy-2,2,6,6-tetramethylpiperidin-1-ol; 4-docosanoxy-2,2,6, 6-Tetramethylpiperidin-1-ol; 4-(phenoxy)-2,2,6,6-tetramethylpiperidin-1-ol; 4-(benzyloxy)-2,2, 6,6-tetramethylpiperidin-1-ol; or 2,2,6,6-tetramethyl-4-(naphth-2-yloxy)piperidin-1-ol.

In some aspects, the compositions of the present disclosure include compounds of formula (I) and formula (II) respectively, wherein R ₁ and R ₂ are the same. For example, in some aspects, the compositions of the present disclosure include compounds of formula (I) and formula (II) respectively, wherein R ₁ and R ₂ are each independently -C(O)(C ₁ -C ₂₂ alkyl ). In some aspects, compositions of the present disclosure include first and second inhibitor compounds of Formula (I) and Formula (II), respectively, wherein R ₁ and R ₂ are different.

The compounds of formula (II) with hydroxylamine disclosed herein have benefits over the corresponding nitrogen oxides (compounds of formula (I)), such as the ability to provide additional polymerization inhibition, as will be explained more fully below. The general synthesis pathway of hydroxylamine that produces nitrogen oxides is to use a reducing reagent to reduce its corresponding nitrogen oxides as follows:

When carbon-centered and oxygen-centered free radical initiators are present, the hydroxylamine of the nitrogen oxide has the potential to provide additional polymerization inhibition compared to the corresponding nitrogen oxide. This system is explained as follows:

Due to the weak NO-H bond of the hydroxylamine of the nitrogen oxide in the compound, the hydroxylamine of the nitrogen oxide is an excellent hydrogen donor and therefore a highly efficient antioxidant. As an antioxidant, hydroxylamine of nitrogen oxides readily reacts with oxygen-centered free radicals (such as peroxide radicals) and is simultaneously converted into its corresponding nitrogen oxides. Nitrogen oxides are often called the most effective inhibitors due to their superior inhibitory capabilities by scavenging carbon-centered free radicals at a nearly diffusion-controlled rate. This rate is several orders of magnitude faster than that of phenolic compounds. However, its kinetic advantages are not always beneficial. For example, oxygen-centered radicals may lose their advantage when present as the dominant radical. Another problem associated with nitrogen oxides is their consumption through non-inhibitory effects and their undesirable reactions with process stream components or other inhibitor additives. Therefore, to achieve a given inhibitory efficacy, high NOx inhibitor doses are often required, thereby making their use economically unattractive or even unfeasible.

In essence, when both oxygen-centered free radicals and carbon-centered free radicals are present, each hydroxylamine of the nitrogen oxide is equivalent to a hydrogen donor plus a nitrogen oxide antipolymerization agent. This system Attractive motivation provided by hydroxylamine of nitrogen oxides. That is, a hydroxylamine of nitrogen oxides can eliminate an oxygen-centered free radical and a carbon-centered free radical, while nitrogen oxides can only eliminate carbon-centered free radicals.

In some aspects, the first inhibitor is a compound of Formula III: (III) wherein R ₃ is –O• or –OH; and R ₄ is C ₁ -C ₂₂ alkyl or aryl, wherein the alkyl and aryl groups are optionally modified by one or more C ₁ -C ₂₂ alkyl substituted by aryl or aryl groups.

In some aspects, R ₃ is –O•. In some aspects, R ₃ is –OH.

In some aspects, R ₄ is C ₁ -C ₂₂ alkyl, optionally substituted with one or more C ₁ -C ₂₂ alkyl or aryl groups. In some aspects, R ₄ is aryl, optionally substituted with one or more C ₁ -C ₂₂ alkyl or aryl groups.

Examples of compounds of formula (III) include, but are not limited to, 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl acetate; 1-oxyl radical-2,2,6 ,6-Tetramethylpiperidin-4-yl propionate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl butyrate; 1-oxyl radical-2 ,2,6,6-tetramethylpiperidin-4-ylvalerate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-ylhexanoate; 1-oxygen Free radical-2,2,6,6-tetramethylpiperidin-4-ylheptanoate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yloctanoate ;1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-ylnonanoate;1-oxyl radical-2,2,6,6-tetramethylpiperidin-4- 1-oxyl decanoate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl undecanoate; 1-oxyl radical-2,2,6,6-tetramethyl Piperidin-4-yl dodecanoate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate; 1-oxyradical-2, 2,6,6-tetramethylpiperidin-4-yl stearate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl benzoate; 1- Oxygen radical-2,2,6,6-tetramethylpiperidin-4-yl palmitate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yl 20 Diacid ester; or 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl 4-tertiary butyl benzoate.

In some aspects, the second inhibitor compound is a phenylenediamine of formula (IV) or formula (V): , (IV) _{( V )} wherein _{X 1 and} Aryl substitution.

In some aspects, the second inhibitor compound is a phenylenediamine of formula (IV). In some aspects, the second inhibitor compound is a phenylenediamine of formula (V).

Examples of phenylenediamines include, but are not limited to, 1,2-phenylenediamine, 1,4-phenylenediamine, N,N'-di-methyl-p-phenylenediamine, N,N'-di-butylene diamine Phenyl-1,4-phenylenediamine, N,N'-di-1,4-dimethylpentyl-1,4-phenylenediamine, N,N'-di-acetyl-1,4- Phenylenediamine, N-tertiary butyl-N'-phenyl-1,4-phenylenediamine, and N,N'-di-phenyl-1,4-phenylenediamine.

In some aspects, the composition includes 2,2',6,6'-tetramethylpiperidinyl-1-oxyl radical and alkyl-substituted 1,4-phenylenediamine.

In some aspects, the composition consists essentially of a first inhibitor compound and a second inhibitor compound. In other aspects, the composition consists of an organic solvent, a first inhibitor, and a second inhibitor.

In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 80% by weight. In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 70% by weight. In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 60% by weight. In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 50% by weight. In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 40% by weight. In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 30% by weight. In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 20% by weight. In some aspects, the first inhibitor compound is present in the composition at a concentration of about 0.01% to about 10% by weight.

For example, in certain aspects, the first inhibitor compound is present at about 0.01% by weight, about 0.1% by weight, about 1% by weight, about 5% by weight, about 10% by weight, about 15% by weight, about 20% by weight, About 25% by weight, about 30% by weight, about 35% by weight, about 40% by weight, about 45% by weight, about 50% by weight, about 55% by weight, about 60% by weight, about 65% by weight, about 70% by weight , is present in the composition at a concentration of about 75% by weight, or about 80% by weight.

In some aspects, the second inhibitor compound is present in the composition at a concentration of about 0.01% to about 50% by weight. In some aspects, the second inhibitor compound is present in the composition at a concentration of about 0.01% to about 40% by weight. In some aspects, the second inhibitor compound is present in the composition at a concentration of about 0.01% to about 30% by weight. In some aspects, the second inhibitor compound is present in the composition at a concentration of about 0.01% to about 20% by weight. In some aspects, the second inhibitor compound is present in the composition at a concentration of about 0.01% to about 10% by weight.

For example, in some aspects, the second inhibitor compound is present at about 0.01% by weight, about 0.1% by weight, about 1% by weight, about 5% by weight, about 10% by weight, about 15% by weight, about 20% by weight, A concentration of about 25%, about 30%, about 35%, about 40%, about 45%, or about 50% by weight is present in the composition.

In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 100:1 to about 1:100. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 90:1 to about 1:90. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 80:1 to about 1:80. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 70:1 to about 1:70. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 60:1 to about 1:60. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 50:1 to about 1:50. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 40:1 to about 1:40. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 30:1 to about 1:30. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 20:1 to about 1:20. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 10:1 to about 1:10. In some aspects, the molar ratio of the first inhibitor compound to the second inhibitor compound is about 1:1.

In some aspects, the composition also includes one or more additional compounds selected from the group consisting of: 2,2,6,6-tetramethylpiperidin-1-oxyl radical; 2,2,6 ,6-tetramethylpiperidin-1-ol; 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical; 4-hydroxy-2,2,6,6-tetramethyl Methylpiperidin-1-ol; 4-side oxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical; 4-side oxy-2,2,6,6-tetramethyl Methylpiperidin-1-ol; 4-acetyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical; 4-acetyloxy-2,2,6,6 -Tetramethylpiperidin-1-ol; 4-propyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical; 4-propyloxy-2,2,6 , 6-tetramethylpiperidin-1-ol; and bis((2,2,6,6-tetramethylpiperidin-1-oxyl radical)-4-yl)oxalate. In some aspects, the composition also includes 2,2,6,6-tetramethylpiperidin-1-oxyl radical. In some aspects, the composition also includes 2,2,6,6-tetramethylpiperidin-1-ol. In some aspects, the composition also includes 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical. In some aspects, the composition also includes 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-ol. In some aspects, the composition also includes 4-side oxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical. In some aspects, the composition also includes 4-side oxy-2,2,6,6-tetramethylpiperidin-1-ol. In some aspects, the composition also includes 4-acetyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical. In some aspects, the composition also includes 4-acetyloxy-2,2,6,6-tetramethylpiperidin-1-ol. In some aspects, the composition also includes 4-propionyloxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical. In some aspects, the composition also includes 4-propionyloxy-2,2,6,6-tetramethylpiperidin-1-ol. In some aspects, the composition also includes bis((2,2,6,6-tetramethylpiperidin-1-oxyl radical)-4-yl)oxalate.

The composition may also optionally include one or more organic solvents. One of ordinary skill in the art will appreciate that there are many organic solvents that are compatible with the compositions of the present disclosure. For example, in some aspects, one or more organic solvents are selected from vinyl acetate, dimethyl phthalate, dimethylformamide, toluene, xylene, highly aromatic naphtha, Acetonitrile, ethyl acetate, acetone, methylene chloride, tetrahydrofuran, hexane, dimethylstyrene, N-methyl-2-pyrrolidone, and combinations thereof. In some aspects, the composition also includes vinyl acetate. In some aspects, the composition also includes dimethyl phthalate. In some aspects, the composition also includes dimethylformamide. In some aspects, the composition also includes toluene. In some aspects, the composition also includes xylene. In some aspects, the composition also includes higher aromatic naphtha. In some aspects, the composition also includes acetonitrile.

In some aspects, the composition also includes one or more ethylenically unsaturated monomers. One of ordinary skill in the art will appreciate that there are many ethylenically unsaturated monomers that are compatible with the compositions of the present disclosure. For example, in some aspects, one or more ethylenically unsaturated monosystems are selected from vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene , (meth)acrylic acid, and combinations thereof. In some aspects, the composition also includes vinyl acetate. In some aspects, the composition also includes acrylonitrile. In some aspects, the composition also includes acrylates. In some aspects, the composition also includes methacrylate. In some aspects, the composition also includes 1,3-butadiene. In some aspects, the composition also includes styrene. In some aspects, the composition also includes isoprene. In some aspects, the composition also includes (meth)acrylic acid.

In some aspects, compositions disclosed herein do not include the 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical. In some aspects, the compositions disclosed herein do not include the 4-side oxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical. In some aspects, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4-side oxy-2,2,6,6-tetramethylpiperidine are not added dimethyl-1-oxyl radical to ethylenically unsaturated monomer.

The present disclosure also relates to methods of inhibiting polymerization of monomers, which include adding the compositions of the present disclosure to the monomers. In some aspects, an effective amount of a composition of the present disclosure is added to the monomer, where an effective amount is any amount sufficient to inhibit polymerization of the monomer. The process flow includes a monomer and microcells.

In some aspects, the monomer is an ethylenically unsaturated monomer. In some aspects, it is disclosed that the monosystem is an ethylenically unsaturated monomer selected from the following: vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, styrene, divinyl Benzene, isoprene, cyclopentadiene, dicyclopentadiene, acrylic acid, (meth)acrylic acid, and combinations thereof. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of vinyl acetate. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of acrylonitrile. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of acrylates. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of methacrylates. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of 1,3-butadiene. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of styrene. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of isoprene. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of acrylic acid. In some aspects, the methods disclosed herein can be used to inhibit the polymerization of (meth)acrylic acid.

The compositions of the present disclosure can be added to the fluid manually or automatically. The composition may also be added continuously and/or intermittently. Automatic addition can be accomplished using a chemical syringe pump. The chemical syringe pump can be programmed to add specific amounts of the polymerization inhibitor composition, or any component thereof, to the fluid at specific time intervals. In an alternative aspect, the chemical syringe pump can be manually controlled to add a specific amount of the polymerization inhibitor composition, or any component thereof, to the fluid. Addition of the polymerization inhibitor compositions disclosed herein to the monomer will thereby inhibit polymerization of the monomer.

In some aspects, the monosystem is provided as a pure liquid. In other aspects, the monomer system is provided in a solution, hereafter referred to as a "monomer solution."

In some aspects, the monomer solution also includes one or more additional components selected from acids, organic solvents, water, and combinations thereof. For example, in some aspects, the monomer solution includes one or more organic solvents selected from the group consisting of: vinyl acetate, dimethyl phthalate, dimethylformamide, toluene, ethyltoluene, xylene, higher aromatics Naphtha, acetonitrile, ethyl acetate, acetone, methylene chloride, tetrahydrofuran, hexane, dimethylstyrene, N-methyl-2-pyrrolidinone, and combinations thereof. In some aspects, the monomer solution includes one or more acids selected from: hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, perchloric acid, formic acid, acetic acid, propionic acid acid, butyric acid, valeric acid, caproic acid, acetic acid, caprylic acid, undecanoic acid, lauric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid. In some aspects, the monomer solution includes water.

In some aspects, the composition is added to the monomer such that the concentration of the first inhibitor compound is from about 0.1 ppm to about 10,000 ppm. In some aspects, the composition is added to the monomer such that the concentration of the first inhibitor compound is from about 0.1 ppm to about 5,000 ppm. In some aspects, the composition is added to the monomer such that the concentration of the first inhibitor compound is from about 0.1 ppm to about 1,000 ppm. In some aspects, the composition is added to the monomer such that the concentration of the first inhibitor compound is from about 0.1 ppm to about 500 ppm.

In some aspects, the composition is added to the monomer such that the concentration of the second inhibitor compound is from about 0.1 ppm to about 10,000 ppm. In some aspects, the composition is added to the monomer such that the concentration of the second inhibitor compound is from about 0.1 ppm to about 5,000 ppm. In some aspects, the composition is added to the monomer such that the concentration of the second inhibitor compound is from about 0.1 ppm to about 1,000 ppm. In some aspects, the composition is added to the monomer such that the concentration of the second inhibitor compound is from about 0.1 ppm to about 500 ppm.

The methods of the present disclosure can be used to inhibit premature polymerization of monomers during the extraction process. During the extraction process, solvents are used to separate the components. The difference in polarity between the extraction solvent and the hydrocarbon layer causes emulsion formation, thereby increasing the risk of emulsion polymerization.

Examples of extraction solvents include, but are not limited to, dimethylformamide (DMF), furfural, acetonitrile, N-methyl-2-pyrrolidone, and the like.

The methods of the present disclosure can also be used to prevent premature polymerization of styrene during manufacturing and purification processes.

The disclosed method can also be used in the butadiene extraction process. This utility results from the equilibrium partition coefficient between polar and non-polar organic phases.

In some aspects, the compositions disclosed herein are used in the distillative purification of olefins. For example, the composition may be added to the process stream before entering the distillation unit, or the composition may be added to the process stream in the distillation unit. Example Example 1: Distribution coefficient

Tests were conducted comparing chemicals currently used in industry (HTEMPO and OTEMPO) with the compositions of the present disclosure. The ester of HTEMPO 1 is 4-acetyloxy-2,2'6,6'-tetramethylpiperidinyl-1-oxyl radical. The ester of HTEMPO 2 is 4-propyl-2,2'6,6'-tetramethylpiperidinyl-1-oxyl radical. PDA is di-secondary-butyl-4,4'-phenylenediamine.

Table 1 shows the partition coefficients for several tests between different solvent combinations. Table 1 Polymerization Inhibitor (PI) Partition coefficient between DMF and hexane HTEMPO 95:5 HTEMPO 1 ester 82:18 HTEMPO 2 ester 77:23 OTEMPO 97:3 Polymerization Inhibitor (PI) Partition coefficient between toluene and water HTEMPO 18:82 HTEMPO 1 ester 92:8 HTEMPO 2 ester 97:3 Example 2: Isoprene polymerization test in DMF at 95°C

Commercial isoprene was passed through an alumina column to remove the stabilizer 4-tert-butyrocatechol. Place 0.2 g of active polymerization inhibitor, 40 mL of heptane, 40 mL of DMF, and stirring rod into a 100 mL jar. The mixture was stirred at room temperature for 30 minutes and allowed to stand for 10 minutes.

DMF phase test: Put 0.2 mL of the bottom layer of the two-layer mixture that was previously allowed to stand, 1 mL of azobisisobutyronitrile (AIBN) (0.0004 g/mL) solution, and 50 g of isoprene into a 100 mL jar. Add DMF to make a solution with a total weight of 100 g. Approximately 10 ml of the above mixture was added to 12 pressure tubes using a stirring rod and heated to 95°C. After 30 minutes, and every 30 minutes thereafter, both tubes were removed from the block and the polymerization reaction was quenched by cooling in an ice bath. The cooled polymer solution was immediately diluted with toluene. Determination of soluble polymers in liquids by turbidity method.

Figure 1 shows that compared to conventional polymerization inhibitors HTEMPO and OTEMPO, the composition of the present disclosure significantly reduces isoprene polymerization. In addition, Figure 1 shows that the combination of stable nitroxide radicals and phenylenediamine results in a synergistic effect.

In Figures 1 and 2, "Prototype Product 1" is about 22 wt.% of 4-acetyloxy TEMPO, about 5 to 8 wt.% of HTEMPO, HTEMPOH, and hydroxylamine of 4-acetyloxy TEMPO , and about 70% DMF, "Prototype Product 2" is "Prototype Product 1" plus PDA, "Commercial Product" is 10% HTEMPO aqueous solution, and "PDA" is as previously defined. Example 3: Isoprene polymerization test in heptane at 95°C

Heptane phase: Put 5.0 mL of the top layer of the two-layer mixture that was previously allowed to stand, 1 mL of AIBN (0.0004 g/mL) solution, and 50 g of isoprene into a 100 mL jar. Heptane was added to make a total weight of 100 g solution. Approximately 13 ml of the above mixture was added to 12 pressure tubes using a stirring rod and heated to 95°C. After 30 minutes, and every 30 minutes thereafter, both tubes were removed from the block and the polymerization reaction was quenched by cooling in an ice bath. The cooled polymer solution was immediately diluted with toluene. Determination of soluble polymers in liquids by turbidity method. The results can be seen in Figure 2. The data used to generate the trend lines in Figure 2 can be found in Table 2. Table 2: Polymerization growth data (based on w/w% of polyisoprene) used in the heptane phase of Figure 2 time Prototype product 1 (nitrogen oxide only) Commercial products Prototype product 2 (PDA plus NOx) PDAs 0 0 0 0 0 30 0.00% 0.01% 0.00% 0.10% 60 0.00% 0.06% 0.00% 0.24% 90 0.00% 0.17% 0.00% 0.45% 120 0.00% 0.23% 0.00% 0.83% 180 0.00% 0.44% 0.00% 1.05% 240 0.00% 0.48% 0.00% 1.20%

All compositions and methods disclosed and claimed herein can be made and performed without undue experimentation in light of the present disclosure. While this invention may be embodied in many different forms, specific preferred aspects of the invention are described in detail herein. This disclosure is illustrative of the principles of the invention and is not intended to limit the invention to the specific aspects illustrated. Furthermore, unless expressly stated to the contrary, use of the term "a/an" is intended to include "at least one" or "one or more". For example, "an inhibitor" is intended to include "at least one inhibitor" or "one or more inhibitors."

Any range given in absolute terms or approximate terms is intended to encompass both, and any definitions used herein are intended to be illustrative rather than restrictive. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are intended to be stated as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, all ranges disclosed herein should be understood to encompass any and all subranges incorporated therein (including all fractional and integer values).

Any composition disclosed herein may comprise, consist of, or consist essentially of any of the elements, components, and/or ingredients disclosed herein or any of the elements, components, or ingredients disclosed herein. Any combination of two or more of them.

Any method disclosed herein may comprise, consist of, or consist essentially of: any method step disclosed herein, or any combination of two or more of the method steps disclosed herein.

The conjunction "comprising" which is synonymous with "including", "containing", or "characterized by" is inclusive or open-ended and does not exclude additional unrecited elements. , components, ingredients, and/or method steps.

The conjunction "consisting of" excludes any elements, components, ingredients, and/or method steps not specified in the scope of the patent application.

The connective "consisting essentially of" limits the scope of the patent application to the specified elements, components, ingredients, and/or steps and those that do not substantially affect the claimed invention ( Multiple) basic and novel features.

As used herein, the term "about" means that the quoted value is within the error resulting from the standard deviation derived from their respective test measurements, and if such errors cannot be determined, then "about" may mean, for example, that within Within 5% of the quoted value.

Furthermore, the present invention encompasses any and all possible combinations of some or all of the various aspects described herein. It is also to be understood that various changes and modifications to the presently preferred aspects described herein will be apparent to those of ordinary skill in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without impairing its intended advantages. Accordingly, it is intended that the changes and modifications described are covered by the appended claims.

without

Embodiments of the present invention are described below with specific reference to the accompanying drawings. [Fig. 1] shows polymerization of isoprene in DMF at 95°C. [Fig. 2] shows polymerization of isoprene in heptane at 95°C.

Claims (20)

A method of inhibiting monomer polymerization, comprising: adding a composition to a process stream in an extractive distillation process, Wherein the composition includes: a first inhibitor compound, which contains stable nitroxide radicals; and a second inhibitor compound, which contains phenylenediamine, The process flow includes microcells. The method of claim 1, wherein the first inhibitor compound has formula (I): (I) wherein R ₁ is a C ₁ -C ₂₂ alkyl or aryl group, wherein the alkyl and aryl groups are optionally substituted with one or more C ₁ -C ₂₂ alkyl or aryl groups. The method of claim 1 or claim 2, wherein the first inhibitor is selected from the group consisting of: 1-oxyl radical-2,2,6,6-tetramethylpiperine-4-ol ; 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxy; 4-ethoxy-2,2,6,6-tetramethylpiperidine-1-oxy ; 4-propoxy-2,2,6,6-tetramethylpiperidine-1-oxy; 4-butoxy-2,2,6,6-tetramethylpiperidine-1-oxy ; 4-pentyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-hexyloxy-2,2,6,6-tetramethylpiperidin-1-oxy ; 4-heptyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-octyloxy-2,2,6,6-tetramethylpiperidin-1-oxy ; 4-Nonyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-decyloxy-2,2,6,6-tetramethylpiperidin-1-oxy ;4-Undecyloxy-2,2,6,6-tetramethylpiperidine-1-oxy;4-Dodecyloxy-2,2,6,6-tetramethylpiperidine- 1-oxy; 4-tridecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-tetradecyloxy-2,2,6,6-tetramethyl piperidin-1-oxy; 4-pentadecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-hexadecyloxy-2,2,6, 6-tetramethylpiperidin-1-oxy; 4-heptadecanyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-octadecyloxy-2, 2,6,6-tetramethylpiperidin-1-oxy; 4-nonadecyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-decyloxy- 2,2,6,6-tetramethylpiperidin-1-oxy; 4-eicosyloxy-2,2,6,6-tetramethylpiperidin-1-oxy; 4-eicosyloxy Monoalkoxy-2,2,6,6-tetramethylpiperidine-1-oxy; 4-docosyloxy-2,2,6,6-tetramethylpiperidine-1-oxy base; 4-(phenoxy)2,2,6,6-tetramethylpiperidine-1-oxy; 4-(benzyloxy)-2,2,6,6-tetramethylpiperidine- 1-oxy; 2,2,6,6-tetramethyl-4-(naphth-2-yloxy)piperidin-1-oxy; and any combination thereof. The method of claim 1, wherein the first inhibitor is a compound of formula III: (III) wherein R ₃ is –O• or –OH; and R ₄ is C ₁ -C ₂₂ alkyl or aryl, wherein the alkyl and aryl groups are optionally modified by one or more C ₁ -C ₂₂ alkyl substituted by aryl or aryl groups. The method of claim 4, wherein the first inhibitor is selected from the group consisting of: 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl acetate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl propionate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl Butyrate; 1-Oxyl-2,2,6,6-tetramethylpiperidin-4-ylvalerate; 1-Oxyl-2,2,6,6-tetramethylpiperidine -4-ylhexanoate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-ylheptanoate; 1-oxyl radical-2,2,6,6-tetramethyl Methylpiperidin-4-yloctanoate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-ylnonanoate; 1-oxyradical-2,2,6 ,6-tetramethylpiperidin-4-yl decanoate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl undecanoate; 1-oxyl radical- 2,2,6,6-tetramethylpiperidin-4-yl dodecanoate; 1-oxyradical-2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexane Acid ester; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl stearate; 1-oxyl radical-2,2,6,6-tetramethylpiperidine -4-yl benzoate; 1-oxyl radical-2,2,6,6-tetramethylpiperidin-4-yl palmitate; 1-oxyl radical-2,2,6,6- Tetramethylpiperidin-4-yl behenate; 1-Oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tertiary butyl benzoate; and any combination thereof. The method of any one of claims 1 to 5, wherein the second inhibitor compound is formula (IV) or a phenylenediamine of formula (IV): , (IV) _{( V )} wherein _{X 1 and} Aryl substitution. The method of any one of claims 1 to 6, wherein the second inhibitor is selected from the group consisting of: 1,2-phenylenediamine, 1,4-phenylenediamine, N,N'- Di-methyl-p-phenylenediamine, N,N'-di-secondary butyl-1,4-phenylenediamine, N,N'-di-1,4-dimethylpentyl-1,4 -Phenylenediamine, N,N'-di-ethyl-1,4-phenylenediamine, N-tertiary butyl-N'-phenyl-1,4-phenylenediamine, N,N'- Di-phenyl-1,4-phenylenediamine, and any combination thereof. The method of any one of claims 1 to 7, wherein the first inhibitor compound is present in the composition at a concentration of about 0.01% by weight to about 80% by weight. The method of any one of claims 1 to 8, wherein the second inhibitor compound is present in the composition at a concentration of about 0.01% by weight to about 50% by weight. The method of any one of claims 1 to 9, wherein the molar ratio of the first inhibitor compound to the second inhibitor compound is from about 100:1 to about 1:100. The method of any one of claims 1 to 10, wherein the composition further contains an organic solvent. The method of any one of claims 1 to 11, wherein the process stream further comprises an ethylenically unsaturated monomer selected from the group consisting of: vinyl acetate, acrylonitrile, acrylate, methacrylate, 1,3-butadiene, styrene, isoprene, cyclopentadiene, dicyclopentadiene, acrylic acid, methacrylic acid, and any combination thereof. The method of claim 12, wherein the process stream further includes at least one polar extractive distillation solvent and at least one non-polar extractive distillation solvent, and the ethylenically unsaturated monomer is present in the at least one non-polar extractive distillation solvent. The method of claim 13, wherein the at least one polar extractive distillation solvent and the at least one non-polar extractive distillation solvent are immiscible with each other, and the ethylenically unsaturated monomer is present in the at least one non-polar extractive distillation solvent. The method of claim 13, wherein the ethylenically unsaturated monomer partitions to a greater extent into one of the at least one non-polar distillation solvent than into the at least one polar extractive distillation solvent. The method of claim 15, wherein the first inhibitor or the second inhibitor partitions to a greater extent into the at least one non-polar extractive distillation solvent than into the at least one polar extractive distillation solvent. The method of any one of claims 13 to 16, wherein the at least one non-polar extractive distillation solvent is selected from the group consisting of: furfural, vinyl acetate, acrylonitrile, 1,3-butadiene, benzene Ethylene, isoprene, cyclopentadiene, dicyclopentadiene, acrylic acid, methacrylic acid, tetrahydrofuran, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane Alkane, tridecane, tetradecane, benzene, toluene, ethylbenzene, ethyltoluene, methylene chloride, tetrachloromethane, pentene, hexene, heptene, octene, nonene, decene, undecene , dodecene, tridecene, tetradecene, cyclopentane, cyclopentene, cyclohexane, cyclohexene, dicyclopentane, cyclopentadiene, dicyclopentadiene, ethyl acetate, propylene Ethyl ester, ethyl butyrate, ethyl valerate, ethyl hexanoate, ethyl enanthate, ethyl, nonanoate, ethyl caprate, ethyl undecanoate, ethyl dodecanoate, thirteen Ethyl acid ester, ethyl myristate, ethyl pentadecanoate, ethyl hexadecanoate, ethyl octadecenoate, ethyl behenate, methyl acetate, methyl propionate, methyl butyrate, Methyl valerate, methyl caproate, methyl enanthate, methyl, nonanoate, methyl caprate, methyl undecanoate, methyl dodecanoate, methyl tridecanoate, methyl myristate , Methyl pentadecanoate, methyl hexadecanoate, methyl octadecenoate, methyl behenate, propyl acetate, propyl propionate, propyl butyrate, propyl valerate, propyl caproate , propyl heptanoate, propyl, nonanoate, propyl caprate, propyl undecanoate, propyl dodecanoate, propyl tridecanoate, propyl myristate, propyl pentadecanoate, hexadecanoate Propyl acid, propyl octacrylate, propyl behenate, butyl acetate, butyl propionate, butyl butyrate, butyl valerate, butyl caproate, butyl enanthate, butyl, Peyronanoate, butyl caprate, butyl undecanoate, butyl dodecanoate, butyl tridecanoate, butyl myristate, butyl pentadecanoate, butyl hexadecanoate, butyl octadecenoate Ester, butyl behenate, hexyl acetate, hexyl propionate, hexyl butyrate, hexyl valerate, hexyl hexanoate, hexyl enanthate, hexyl, nonanoate, hexyl decanoate, Hexyl monoate, hexyl dodecanoate, hexyl tridecanoate, hexyl myristate, hexyl pentadecanoate, hexyl hexadecanoate, hexyl octadecenoate, hexyl behenate, acetic acid Octyl ester, octyl propionate, octyl butyrate, octyl valerate, octyl hexanoate, octyl enanthate, octyl, nonanoate, octyl caprate, octyl undecanoate, octyl dodecanoate, octyl tridecanoate, Octyl myristate, octyl pentadecanoate, octyl hexadecanoate, octyl octadecenoate, octyl behenate, and any combination thereof. The method of any one of claims 13 to 17, wherein the at least one polar extractive distillation solvent is selected from the group consisting of N,N-dimethylformamide, furfural, N-methylpyrrolidone, acetonitrile, water, and its combination. The method of any one of claims 1 to 18, wherein the composition is added to the process stream such that the concentration of the first inhibitor compound is from about 0.1 ppm to about 10,000 ppm. The method of any one of claims 1 to 19, wherein the composition is added to the process stream such that the concentration of the second inhibitor compound is from about 0.1 ppm to about 10,000 ppm.